Morphology-controlled synthesis of MoO3 nanostructures and its effect on heavy metal ion detection

The threat of heavy metal ions (HMIs) in aqueous media to public health is gaining its concern all around the world. Thus, to measure the concentration, lower than the regulated level, synthesis of MoO3 nanostructures using hydrothermal method was carried out. In this study, MoO3 was synthesized from an aqueous solution containing ammonium heptamolybdate and different concentrations (0.1 and 0.3 M) of polyvinylpyrrolidone (PVP). Here, PVP stabilizes the particles and prevents them from agglomeration. X-ray diffraction analysis revealed an orthorhombic structure. Field emission scanning electron microscopy revealed that various concentrations of PVP are responsible for morphological modifications. A structure resembling a plate-like morphology were observed at 0.3-M PVP. According to UV-Vis spectroscopy, the bandgap energy is directly proportional to PVP concentration. Electrochemical analysis was used to evaluate the capabilities of synthesized nanostructures for HMIs detection. According to electrochemical experiments, the linear detection range for Pb (II) is 0.02-90 ppb. The higher surface area induced by the presence of PVP improved the material sensitivity by similar to 2 times as compared to material synthesized without PVP. Additionally, synthesized MoO3 showed good selectivity toward Pb (II) than other HMIs. According to electrochemical studies, this research gives a valuable insight for understanding the effect of morphology on HMIs detection.